Ti Single Atom Enhancing Pt-Based Intermetallics for Efficient and Durable Oxygen Reduction

Abstract

The insufficient durability of Pt-based catalysts and the sluggish kinetics of oxygen reduction reaction (ORR) is hampering the development of proton exchange membrane fuel cells (PEMFCs) for commercialization. Herein, a single atom Ti-modified activated nitrogen-doped porous carbon (Ti-a-NPC) is designed to equalize O2-activation/*OH-removal through regulating the charge rearrangement of ultra-small L12-Pt3Co for efficient and durable oxygen reduction. The Ti single-atom modified in the surface/pore of Ti-a-NPC can anchor the Pt-based intermetallic nanoparticles (NPs) not only guarantees Pt-based intermetallics’ ultra-fine size (≈2.62 nm) but also maintains Pt-based intermetallics during ORR process. The enhanced catalyst (L12-Pt3Co/Ti-a-NPC) achieves 11-fold mass activity (1.765 A mgPt−1) compared to commercial Pt/C. Notably, after 30 000 cycles of accelerated durability tests, the mass activity of the L12-Pt3Co/Ti-a-NPC only decreased by 3.7%, while that of commercial Pt/C decreased by 37.1%. Rationalized by theoretical simulation, the introduction of Ti atoms can form charge channels between L12-Pt3Co NPs and Ti-a-NPC, accelerating the charge transfer in the ORR process. Furthermore, the charge of L12-Pt3Co will accumulate to Ti atoms and buffer the electron transfer of L12-Pt3Co to the N atoms, thus optimizing the adsorption performance of the active site to the oxygen-containing intermediate and improving the intrinsic activity of the catalyst.